Prick attachment for pencils.



G. N. SMITH, JR. PRICK ATTACHMENT FOR PENCILS.

APPLICATION FILES NOV- 22. 1916.

Patented Mar. 27,1917.

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%liis invention relates to a simple attachment for drawing pencils,enabling a draftsman, by invertin his pencil, to prick a dot in thepaper. T e use of a sharp pointed implement to prick the paper to locatecenters for circles, the intersection of lines, the contour of atemplet, etc., is very customary with many draftsmen, but to lay downthe pencil and pick up a separate pricking instrument necessarily causesconsiderable Waste time in the aggregate. By mounting a prickingattachment on the head end of the pencil the device is always at handready for use by simply inverting the pencil.

As the pricking point is very sharp, I provide a protecting casin withinwhich it normally stands, so that .t ere is no danger either of thedraftsman injuring himself or of his dulling th point. When the pencilis inverted the prick point drops by gravity into active position. Tohold the point in this position for use I provide a normally idlelocking dog, at the side of the attachment, which may be readily pressedby the users finger into place to lock the point in its rojectingposition.

Mg attachment is hereinafter more fully explained, in connectionwith theaccompanylng drawing, and its essential characteristics are summarizedin the claims.

In the drawing, Figure 1 is a side elevation of a pencil equipped withmy pricking attachment. This view shows the device in the position foruse, the operators finger, locking the extended point, being illustratedby broken lines. Fig. 2 is an enlarged side elevation of the attachmentand a portion of the pencil, this view showing the locking dog ininactive position in full lines, and in active position in broken lines.Fig. 3 is a Specification of Letters Patent.

Patented Mar. 2t, IWJW.

Application filed November 22, 1916. Serial No. 18%,735.

side elevation of the prick point on' an enlarged scale; Fig. 4 is aside elevation of the attachment in idle position on the head end of apencil; Fi 5 is a side elevation of the attachment, loo ing from theside where the locking dog is located, the point being omitted; Fig.6'is an axial section through the casing and locking dog; Fig. 7 is anend view of the attachment. 60

As shown in the drawing, 10 indicates the casing of the attachment,which is a tubular member open at one end and having at the other end ahead 11, through which there is a central aperture 12. The interior ofthe casing may be of any desired shape, but I prefer to make itcylindrical and provide it with internal threads, indicated at 14 inFig. 6. The casing can thus convenientlyscrew onto the usual hexagonaldrawing pencils (the edges being rounded ofi if necessary) as well asonto round pencils.

The brick point is designated 20. It is shown as consisting of a taperedor conical portion coming to a sharp point, a cylindrical shank 21,forming an extension of the large end of the cone, and a disk-like head22. The head is of such size as to substantially fill, but slide freelywithin, the bore of the casing. The shank 21 is of a diameter slightlysmaller than that of the aperture 12, so that in use the tapered pointand the shank 21 may pass out of this aperture. When the pencil is usedfor drawing the head 22 rests on the upper end of the pencil A and thesharp end of the point is within the aperture 12, and protected thereby,as clearly shown in Fig. 4. When this pencil is inverted the point dropsby gravity, so that the head 22 rests on the inner face of the end wall11, as shown in Fig. 2.

To look the point in its extended position, I provide a dog consistingof a block or bolt secured to a leaf spring 31 which lies alongside ofthe casing and at its other end is anchored thereto. An opening 15 ismade in the casing opposite the point of the bolt 30. Ordinarily thisdog stands in the position shownin full lines in Fig. 2 and also in Fig.6, but when the prick point has been 100 projected by the inversion ofthe pencil the free end of the spring is pressed inwardly,

as shown in Fig. 1,.thus bringing the bolt 30 above the head 22 of theprick point, as

shown in dotted lines in Fig. 2. This effectively locks the prick pointin active position.

I find it convenient to secure the bolt 30 to the leaf spring by makingan opening through the spring and passing an extension of theboltthrough the opening and up setting or riveting this extension on theouter side of the spring, as shown at 35. The bolt is preferably beveledat its engaging corner 36, to allow it to readily ride over the head 22.The anchored end of the spring is preferably secured to the casing byrivets. I have shown two of these rivets 37 passing through the springand the casing. In order that the inner riveting heads shall not be inthe way of the pencil I distort the casing outwardly at this point, asshown at 38, to provide a recess to be occupied by the rivet heads, andalso a flat seat for the spring.

It will be seen that my attachment is simple and cheap in constructionand ma readily fit anyeordinary pencil. When t e pencil is used indrawing the attachment is out of the way and there is no pointprojecting, but a mere inversion of the pencil, done by the fingers ofthe operators right hand, causes the point to project, after which it islocked by pressing in the spring, preferably by the first or secondfinger.

Having thus described my invention, what' I claim 1s:

1. In an attachment of the character described, the combination of acasingadapted to fit the head end of a pencil, a movably mounted prickpoint within the casing and adapted .to be projected beyond the endthereof, a locking dog carried by the casing for holding the prick pointin active posie tion, and means tending to hold the locking dog ininactive position.

2. In an attachment of the character described, the combination of acasing adapted to fit the head end of a pencil, a movably mounted prickpoint carried thereby and adapted to be projected beyond the endthereof, and a locking device for holding the prick point in activeposition, consisting of a leaf spring secured to the casing and adaptedto be pressed inwardly at its free end and carrying means at such end toengage the prick point.

3. In an attachment of the character described, the combination of acasing adapted to fit around the head portion of a pencil,having aheadwith an aperture through it, a movableprick point within the casingadapted to extend through the aperture and having a head adapted to abutthe inner face of the head of the casing, and a locking device oar- 4.In a device 0 the character described the combination of a casing havinga head with an aperture through it, a prick point within the casingadapted to extend through the aperture and having ahead movab y confinedby the head of the casing, a leaf spring anchored at one end to thecasing, and means carried by the free end of the leaf spring and adaptedto be pressed inwardly to engage and lock the head on the prick point.

5. The combination of a tubular casing having a head with an openingthrough it, a prick point having a head within the casing and a shankadapted to extend out through the opening, a leaf spring anchored at oneend to the casing and at the other end carrying a bolt for engaging thehead of the rick point, there being an opening throug the casing throughwhich the bolt operates.

6. The combination of a tubular casin having a head at one end with acentra opening through. it, a prick point having a central shank adaptedto extend through said opening and having a head lying within thecasing, a locking bolt adapted to be extended through an opening in thecasing to lie against the inner side of the head, and means operablefrom the exterior carrying said bolt.

7. The combination of a tubular casin having a head at one end with acentra opening through it, a prick point having a central shank adaptedto extend through said opening and having a head lying within thecasing, a locking bolt adapted to be extended through an opening in thecasing to lie against the inner side of the head, and a leaf springlying. along the casing on its outer side, the free end of the springhaving the bolt secured to it, the other end of the spring beinganchored to the casing.

8. The combination of a casing having a head with an aperture, a prickpoint havin a head within the casing and a shan adapted to extendthrough the aperture, a leaf spring on the outer side of the casinganchored at one end to the casing, a bolt riveted to the leaf spring atits inner end, there being an opening through the casing opposite theend of the bolt and the bolt being positioned so that when pressedinwardly through the opening it may engage the head of the prick point.

9. The combination of a casing having a head with an aperture in it, aprick point 1 outer side of the casing and secured to said springengaging the outer face of said oflset offset portion. portion andanchoredthereto by a rivet, the 10 10. The combination of a casinghaving a inner head of. which" is within the recess head with an openingin it, a prick point of the offset, and a locking bolt for the prickhaving a shank adapted to extend out of the point carried by the freeend. of said spring.- opening and having a head within the cas- Intestimony whereof, I hereunto aflix my ing, the wall of the casingadjacent to its signature;

other end being ofi'set outwardly, a leaf 7 GEORGE N. SMITH, JR,

